Who viewed your Profile Fb
Regular users can see a recent list of who has been spying on you, along with some basic analytics, while paid users can see up to 90 days worth of viewers, as well as more detailed analytics. It's great for seeing potential job interest and company prospects.
Many rumors on the web claim that Facebook secretly exposes your recent visitors in an array variable (aka: a list of IDs) in the page source code called the InitialChatFriendsList. While this variable does not actually contain the IDs of people stalking your profile, it does give us an interesting peek into how Facebook's algorithms rank your relationships with your friends.
Facebook prioritizes the friends in your chat list using an internal (not-publicly documented) algorithm that appears to be based off of how often you communicate with each of your friends. From my research it appears to take into account recent interactions (in messages, chat, or comment threads) and frequency of recent chats.
It's rumored across the web that the person located at the very top of your "InitialChatFriendsList" is the person who last looked at your profile, but this is wrong. People you never have contact with will most likely be at the very bottom, and those that you communicate with more frequently will probably be up top.